1. Field of the Invention
The invention relates in general to a power supply device, and more particularly to a battery power supply device with self-learning procedure.
2. Description of the Related Art
Referring to FIG. 1, a block diagram of a first conventional power supply device is shown. A power supply device 100 includes an AC-DC power converter 102, a connector 104, a charging circuit 106, a first switch 108, a battery module 110, a micro-controller 112 and a loading device 114. The power supply device 100 provides required power to the loading device 114, and the loading device 114 can be a notebook computer for instance. The AC-DC power converter 102 receives and converts an alternating current power AC to a direct current power DC. The alternating current power AC can be an electric supply of AC110/220V for instance. The direct current power DC provides required power to the notebook computer 114 via the connector 104, or by way of using the charging circuit 106 to charge the battery 110. Meanwhile, the battery does not provide any power to the notebook computer 114 during charging. When the alternating current power AC is not received by the AC-DC power converter 102, the first switch 108 is switched on by the micro-controller switches, so that the output voltage of the battery is provided to the notebook computer 114 via the first switch 108.
The battery 110 has a current gauge IC (not shown in FIG. 1), which gauges the current flowing into and from the battery 110 to measure the power of the battery 110. After being charged and discharged repeatedly, memory effect would occur to the battery 110, so that the power storage of the battery 110 becomes lower and lower. Consequently, after a long duration of usage, the battery 110 must execute a self-learning procedure for the storage of the power of the battery 110 to be gauged precisely. According to the procedure, the battery 110 is first fully charged and then fully discharged. When the battery 110 is being discharged, the current flowing into and from the battery 110 is gauged by the current gauge IC to gauge the magnitude of the power currently stored in the battery 110. For the battery 110 to be “fully discharged”, the voltage of the battery 110 has to be discharged to be lower than an end voltage, which is a voltage value defined by the manufacturer of the current gauge IC. When the voltage of the battery 110 gauged by the gauge IC is lower than the end voltage, the battery 110 is determined to be low-battery. Therefore, if using the self-learning procedure of the battery, the user must fully discharge the battery 110, so that the current gauge IC is still able to precisely gauge the storage of the power of the battery 110 after a long duration of usage.
When the self-learning procedure of the battery needs to be executed, the power supply device 100 uses the charging circuit 106 to fully charge the battery 110, then fully discharge the battery 110. However, when the battery is discharged, the conventional direct current power DC is outputted to the notebook computer 114 continuously because the AC-DC power converter 102 cannot be switched off automatically. Therefore, the power supply device 100 would request the user to unplug to cut off the electrical connection between the AC-DC power converter 102 and the electric supply for the battery 110 to discharge to the notebook computer 114. For example, when the power supply device 100 is used in the notebook computer 114, the program uses a message window to inform the user to unplug the AC-DC power converter 102 from the electric supply. Next, the micro-controller 112 controls the first switch 108 to be switched on for the battery 110 to discharge to the notebook computer 114 via the first switch 108 until the voltage of the battery 110 is fully discharged, that is, below the end voltage. However, this practice requires manual operation, thus causing inconvenience and burden to the user.
Referring to FIG. 2, a block diagram of a second conventional power supply device is shown. A second switch 116 is added to the power supply device 100′. The second switch 116 is coupled to between the AC-DC power converter 102 and the notebook computer 114. The micro-controller 112 is used to control and switch off the second switch 116 for the second switch 116 to be disconnected from the direct current power DC provided by the AC-DC power converter 102. So, the battery 110 can discharge to the notebook computer via the first switch 108 automatically without bothering the user to unplug the AC-DC power converter 102 from the electric supply. However, this would cause the direct current power DC provided by the AC-DC power converter 102 to be completely isolated. Accordingly, when the user unplugs the battery 110, the power of the notebook computer 114 being cut off abruptly may cause data loss to the computer. This practice not only incurs extra costs regarding the installation of the second switch 116, but also brings about extra risk of data loss.